The present invention is related to a pneumatic tool, and more particularly to a rotational speed adjustment mechanism of a pneumatic tool.
There are various conventional rotational speed adjustment mechanisms for controlling the rotational speed of the rotor of a pneumatic tool by means of controlling the flow of the air. In the conventional rotational speed adjustment mechanisms, a specially shaped valve stem is disposed in the air way between the air room and the internal intake passage of the handle for changing the rotational speed of the rotor. It is uneasy to manufacture and process the specially shaped valve stem. Therefore, it is hard to control the precision of the valve stem.
Furthermore, the entire rotational speed adjustment mechanism is disposed in a middle position of the air way of the pneumatic tool. Therefore, when the high pressure air is filled up in the intake passage, the air pressure will lead to leakage of a part of the air. As a result, the energy is partially wasted.